Skin-contact adhesive products, such as bandages, tapes, dressings and the like, generally contain a protective layer, that is, a backing substrate or facestock, and an adhesive to promote adherence of the protective layer to the skin. In order to provide comfort to the wearer of the skin-contact adhesive product, the protective layer, or facestock, has been designed to be flexible and conformable to the skin of the wearer. Adhesives have been formulated which provide adherence of the product to the skin, while still exhibiting the necessary degree of release when intentionally removed so as not to tear the skin which it contacted, and not to leave adhesive residue on the skin after removal. Skin-contact adhesives must also be formulated so as not to contain ingredients which irritate damaged skin or the surrounding healthy skin.
Pressure sensitive adhesive bandages and medical tapes have existed for a long time. Their constructions are similar but differ in that an adhesive bandage normally has a gauze bonded to the adhesive and is protected by a release liner. In addition, adhesive bandages are produced in a greater variety of shapes and sizes than tapes. The adhesives and backing materials for both may be the same, however. Both require the ability to be sterilized without material loss of adhesive properties and it is desirable for the adhesive to be hypoallergenic. This is not a characteristic of natural rubber based adhesives.
A medical tape is typically slit from a roll of a facestock or backing having on at least one surface thereof an adhesive which will adhere to skin under all conditions without irritation, yet will not have an adhesion so great that the tape can be removed only with accompanying discomfort.
Bandages have the same requirement but differ from tapes in that they are die cut to select sizes, with the adhesive being protected by a discardable release liner and a portion of the adhesive surface being bonded to a gauze which covers a wound. Traditionally used adhesives include natural rubber based adhesives which are not hypoallergenic.
One class of adhesive bandage is intended for use by physically or athletically active people. This adhesive bandage is characterized by enhanced flexibility and water resistance, permitting freedom of movement during exercise and resisting peel-off due to skin perspiration or contact with water.
An acceptable adhesive bandage must have a backing material which is flexible yet strong, and an adhesive which is able to be removed without skin irritation, yet tenacious enough to conformably adhere to the skin during movement and when in contact with water or skin perspiration. Additional requirements are aging stability and the capability of being subjected to sterilization procedures without degradation of performance.
The adhesive must exhibit a balance between its shear properties and adhesion, which are inversely related. In a "wet flex" performance test for adhesive bandages, when applied to fingers, the failure modes are "flagging", that is, when the overlapped bandage pops open due to a failure to adhere to itself, and "ring off", when the overlapped bandage loses adhesion to the skin and slips off. Conversely, an adequate degree of shear is required so that no adhesive residue remains when the bandage is removed from the skin of the wearer.
It is therefore an object of the present invention to provide a pressure sensitive adhesive bandage or medical tape which exhibits wet flex characteristics.
It is a further object of the invention to provide a bandage or medical tape which carries a pressure sensitive adhesive exhibiting both good adhesion to self, and no adhesive residue on skin upon removal.
It is a further object of the present invention to provide a pressure sensitive adhesive bandage or medical tape which exhibits aging stability.
It is a further object of the invention to provide an adhesive bandage or medical tape which is capable of being subjected to conventional sterilization techniques without degradation of the adhesive performance.